Tuning unit for radio receivers



Aug 5, 1941- A. B. WINCHELL TUNING UNIT FOR RADIO RECEIVERS Filed June11, 1938 2 Sheets-Sheet 1 INVENTUR ATT URNEY Aug 5, 1941. w Nc 2,251,476

TUNING UNIT FOR RADIO RECEIVERS Filed June 11, 1958 2 Sheets-Sheet 2 .98 E77 F g 9 l I 4-3 INVENTEIR ARTHUR HWINBHELL ATTORNEY Patented Aug. 5,1941 UNITED STATES PATENT QFFIQE TUNING UNIT FOR. RADIO RECEIVERSApplication June 11, 1938, Serial No. 213,299

18 Claims.

This invention relates to improvements in a station selector or tuningunit for a radio receiving apparatus. The invention pertains moreparticularly to a mechanical mechanism having a plurality of manuallyoperated control or selector members, the setting of any one of whichwill operate a variable condenser unit to tune the radio receiving setto the frequency of a corresponding one of a plurality of pre-selectedbroadcasting stations without the usual necessity of more or lesscritically adjusting the main tuning control of the receiving set, whichconventionally includes a tuning knob and a dial associated with gangedvariable condensers.

The main object of this invention is to provide simply and durablyconstructed mechanical tuning means which may be readily connected withthe operating shaft of a variable condenser, or a plurality of suchcondensers of a radio receiving set, and which is provided with aplurality of manually operated selector means, each of which is arrangedfor setting the condenser or condensers for a corresponding one of aselected group of broadcasting stations.

A more specific object of the invention is to provide a multiple controltuning unit for operating a variable condenser which is constructed sothat the maximum movement of the condenser may be produced by arelatively small amount of movement of any one of a plurality ofmanually operated selector members.

'Another object of the invention is to provide a tuning unit of theabove mentioned class having the manually operated selectors providedwith relatively movable selector elements which may be adjusted at anytime to change the setting of the variable condenser produced thereby,

that the selector elements may be quickly and, easily adjusted toproduce a desired setting of the condensers associated with the tuningdial.

Other objects and advantages of my invention will be apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

Figure 1 is a top plan of a tuning unit embodying the various featuresof this invention, portions of the unit being shown broken away and insection, and the drive member or shaft thereof being illustratedconnected with the shaft of a variable condenser.

Figure 2 is a transverse sectional view taken in the plane of the line2-2, Figure l, illustrating a manually operated selector member in thenormal or outer inoperative position.

Figure 3 is a transverse sectional view taken on line 3-3, Figure 1, andillustrating a manually operated selector member in an intermediateposition.

Figure 4 is a transverse sectional view similar to Figure 3,illustrating the manually operated selector member in the inner oroperative position.

Figure 5 is a detail transverse sectional view taken substantially onthe line 5-5, Figure 6, illustrating an inner portion of the togglemechanism for operatively connecting the manually operated selectormembers with the drive shaft in the intermediate position illustrated inFigure 3.

Figure 6 is a detail vertical sectional view through the togglemechanism positioned at one end of the tuning unit taken substantiallyon line 6-6, Figure 3.

Figure 7 is a detail vertical sectional view taken on line 1-4, Figure3.

Figure 8 is a transverse sectional view similar to Figure 3,illustrating a modified form of linkage mechanism and is takensubstantially on line 88, Figure 9.

Figure 9 is a detail vertical sectional view taken on the line 99,Figure 8.

Figure 10 is a detail sectional view similar to Figure 8 takensubstantially on line llll9, Figure 11, and illustrates a furthermodification of the linkage structure.

Figure 11 is a longitudinal vertical sectional view taken substantiallyin the plane of the line ll-ll, Figure 10, the central portion of theframe and selector mechanism being broken away.

My novel tuning unit, as illustrated in Figures 1 to 7, inclusive, ofthe drawings, comprises a substantially rectangular frame H3 adapted tobe supportably connected in any suitable manner to the chassis of aradio receiving apparatus. This frame comprises a front plate II, a backplate I2 and two end plates l3. Journaled in the frame Ill, in inwardspaced substantially parallel relation to the rear plate I2, is a driveshaft l5 which has the ends thereof extending beyond the side plates I 3of the frame and adapted to be connected in any suitable manner with avariab e condenser, as indicated at C, Figure 1.

connected thereto at one end by a suitable flexible coupling or otherconventional means, whereby rotation of the drive shaft will produce acorresponding rotation of the condenser shaft S and the rotor plates Rconnected therewith. The end of the drive shaft l5 opposite thecondenser C is shown projecting a short distance beyond the adjacent endof the frame l0 and may be connected in any suitable manner to the usualtuning knob and dial spindle of the receiving set whereby said shaft maybe manually operated in the conventional manner for adjusting thecondenser C during the tuning operation.

Mounted in the frame I0 is a plurality of, in this instance six,manually operated selector or control members H which extendtransversely through the frame ID in a substantially horizontal planebeneath the drive shaft .|'5, as illustrated more particularly in Figure2. Each of these selector members comprises a push rod 2| having theforward portion |8 thereof reduced in diameter and slidably androtatably received in a corresponding aperture l9 formed inthe frontplate II of the frame I0. Each of these portions I8 of the push bars isadapted to extend beyond the front plate II and through the front panelof the radio receiver cabinet into a convenient position to be manuallyoperated from the exterior of said cabinet. A pushbutton 20 may, asshown, be secured to the forward end of each push rod 2| to provide aconvenient finger piece by which the rod may be rotated as well aspushed axially for a purpose which will hereinafter be explained.

Each of the push rods 2| has the forward end thereof provided with atransversely disposed slot 22 adapted to receive a screw driver or otherimplement by which the rod may be rotated. These rods may, as shown inFigures 1 and 2, terminate a short distance inside the push buttonconnected therewith and each push button is provided with a slot orrecess 23 in the outer end thereof in registration with the rod slot 22to allow the screw driver to engage in the latter slot. Each rod 2| isprovided with a right-hand screw-thread 24 formed on the portion thereofadjacent the portion l8 and a left-hand screwthread 25 formed on anintermediate portion thereof adjacent the threads 24, the latter screwhaving the same number of threads per inch as the screw-threads 24. Therear end portion 26 of each rod 2| is shown slightly reduced indiameterand extended through a suitable aperture 21 formed in the rear plate i2for both rotary and sliding movement with respect tosaid plate.

Mountedrupon the reduced portion 25 of each rod 2| is acompressionlspring 28 which has one end thereof arranged in engagementwith the inner face of the rear plate I2 and the other end arranged incontactwith a washer 29 mounted on the reduced portion 26 of the rodincontact with a shoulder 30 formed at the junction of the reduced portion26 and the screw-threaded portion 25 of said rod.

Mounted upon each rod 2| is a pair of actuating members 32 and 33, oneof which has screw-threaded engagement with the screwthread 24 and theother actuating member has screw-threaded engagement with the left-handscrew-threads 25. Each of these actuating members is formed from asubstantially flat bar provided with a tail piece 32 or 33',respectively. These tail pieces are arranged side by side and extendthrough a suitable aperture l2 provided in the rear plate i2 at one sideof the aperture 21 for the push rod end 26, as illustrated in Figure 1.The forward end of each actuating member 32 is provided with a portion34 which extends laterally from the portion 32 thereof and which isprovided with a screw-threaded aperture 34 receiving the portion 24 ofthe corresponding rod 2|. Each bar 32 is also provided with a pendentportion or head 35 which extends downwardly therefrom adjacent thetransverse portion 34 to a position substantially in the plane of thelower side of the frame If].

Each of the other actuating members or bars 33 is provided with alaterally disposed portion 33, intermediate the ends thereof, which isprovided with a screw-threaded aperture and which receives thescrew-threaded portion 25 of the corresponding rod therein. I Each ofthe bars or actuating members 33 is provided with an extension 31 whichprojects forwardly from the lateral portion 36 at the side thereofopposite the portion 33 and in substantially parallel relationtherewith. The forward end of the portion 31 is provided with anupwardly extending portion or head 38 which terminates in substantiallythe horizontal plane of the upper face of the frame ID, as illustratedin Figures 2, 3 and 4.

It will now be observed that the heads 35 and 38 for each reciprocatingrod 2! are arranged at opposite sides of said rod and that these headswill be moved in reverse directions with respect to each other and tothe rod as said rod is rotated in one direction or the other due to thescrew-threaded engagement of the bars 32 and 33 with the respectiveright-hand and lefthand screw-threads 24 and 25 provided on the rod.Also, it will be seen that, due to this arrangement, the head 38 may bemoved by rotation of the rod 2| connected therewith from a position infront of the head 35 to a position at the rear of said head, as desired.In order that the push rod 2| may not be accidentally rotated by objectscoming in contact with the forward exposed ends thereof or with the pushbuttons 20, an appreciable amount of friction is maintained between thescrew-threads onthe rods and those on the selector bars by bending thetransverse portions of at least one of the selector bars as the bars 32so that said portions Will be normally maintained at a slight angle tothe normal position thereof with respect to the push rods 2| associatedtherewith.

It will now be understood that when the rods 2| are moved longitudinallywith respect to the frame |0 against the action of the correspondingsprings 28 by pressure exerted upon the outer ends of the push rods 2|,the actuating members 32 and 33 and the heads 35 and 38 associatedtherewith Will also be moved in unison with said rods. This movement ofthe bars 32 and 33 is for the purpose of bringing the heads 35 and 38into cooperative engagement with a suitable linkage mechanism associatedwith the drive shaft |5- for rotating said shaft.

This linkage mechanism, as 40, comprises a pair of rock arms 4| mountedupon the drive shaft l5 adjacent the side plates l3 of the frame NJ, asshown in Figure 1. Each of these arms 4| is a substantially U-shapedmember which is clamped to the shaft |5 by a screw 42 mounted in the'transverse portion of the arm. The outer or free ends of each rock arm4| is connected by a pair of links 43 with corresponding ends of a pairof rock levers 44 and 45 which are rotatably mounted upon a pivotal postor stud 46. As shown in Figure 1, there are two of the pivotal members45 arranged one at either end of the frame l0. Each of these members 46is provided with a screw-threaded portion 41 which extends through asuitable aperture formed in the adjacent side plate l3 of the frame andis clamped to said side plate by a nut 48 mounted on said screwthreadedportion.

The inner end of each pivotal member 46 is reduced somewhat in diameter,as at 41, and rotatably supports the adjacent rock levers 44 and 45thereon. These levers are maintained in spaced relation to each other bya suitable spacing sleeve 49 mounted on the portion 41 of thecorresponding stud 46 between the levers 44 and 45, as illustrated inFigure 6. The pivotal studs 45 are connected with theframe ID in coaxialrelation with each other and so as to lie in substantially thehorizontal plane of the push rods 2| a short distance infront of thevertical plane passing through the drive shaft l5. The inner positionedrock levers 45, as shown, are construoted alike and extend. somedistance above the pivotal studs 46 and. are tied together at theirupper ends by a suitable tie-rod 50 which extends longitudinallywithinthe frame H] in a horizontal plane above the push rods 2| and inthe path of movement of the actuating heads 38. Similarly, the outerpositioned rock levers 44 are constructed alike and are connected witheach other by a tie-rod 5| which extends in substantially a horizontalplane longitudinally within the frame below the push rods -2| and in thepath of movement of actuating heads 35. The tie-rod extends throughclearance openings 45' provided in the levers 45.

The distances from the common axis of rotation of the levers 44 and 45to the tie-rods 58 and 5| are substantially equal. Furthermore, thedistances from the common axis of rotation of the levers 44 and 45 tothe pivotal connections 53 between these levers and the links 43 aresubstantially equal. 'It therefore follows that for each degree ofmovement of the tie-rods 50 and 5| about the axes of the pivotal studs46, a uniform degree of movement of the pivots 53 and; therefore, of thearms 4| will be produced.

In the construction shown in the drawings, the distances from the commonaxis of swinging movement of the levers 44 and 45 to the pivots 53 aresubstantially twice the distances from said axis to the axes of thetie-rods 50 and 5|, while the distance from the axis of the drive shaft|5 to the pivot connection, as 54, of the arms 4| with the links 43 isslightly less than the distance from said common axis of rotation of thelevers 44 and 45 to the tie-rods58 and 5| so that the degree of rotationof the shaft l5 produced by engagement of the heads 35 and 38 with thetierods 5| and as each push rod 2| is moved inwardly against the actionof the corresponding spring 28. The tie-rod which is nearest itsactuating head 35 or 38 when said heads are in their normal outermostposition will, of course, be engaged first by said head and be swungrearwardly thereby. This rearward movement of one of the tie-rods willeffect a corresponding forward swinging movement of the other tie-roddue to the connection of said rods with each other, provided by levers44 and 45, links 43 and arms 4|. This forward swinging movement of oneof the rods 59 or 5| will continue until said rod is engaged by itsactuating head 35 or 38, whereupon the rods and heads will be heldagainst further movement in their respective directions. It thereforefollows that the rock levers 44 and 45, arms 4| and the drive shaft |5will be moved to a predetermined position upon each inward stroke of anactuating member I? and the direction of rotation of the shaft |5 willdepend upon which of the two tie-rods of the linkage mechanism is firstengaged by an actuating head.

When it is desired to adjust or set the tuning unit so that themanipulation of a predetermined one of the reciprocating control orselector members ll will set the variable condenser C to the frequencyof a selected broadcasting station, the heads 35 and 38 of that selectormember H are moved inwardly by pressure exerted upon the outer end ofthe corresponding push bar 2| until both heads contact with the tie-rods50 and 5| As the heads 35 and 38 thus engage the tierods 50 and 5| thefrequency to which the condenser is then tuned may be readily determinedby observing the setting of the usual tuning dial associated therewith.If the tuning dial indicates that the condenser is not tuned to thefrequency of the station selected, the selector member I! is adjusted toproperly set the condenser in the following manner: The push rod 2| isrotated by means of the push button 28 or a screw driver engaging in theslot 22, While the heads 35 and 38 are being firmly maintained againstthe tierods, in a direction to move said heads toward or from eachother, depending upon the direction it is desired to rotate thecondenser shaft S for tuning the condenser to the desired station. Thismovement of the heads 35 and 38 toward or from each other will produce acorresponding rotation of the levers 44 and 45 about the axes of thepivotal studs 45, and this rotation of the levers will produce acorresponding movement of the rock arms 4| and shaft l5.

It will be understood that rotation of shaft l5 will produce acorresponding rotation of condenser C and also of the tuning dialassociated with said condenser and shaft. It follows, therefore, thatthe push rod 2! may be rotated in the proper direction until the tuningdial indicates that the condenser is tuned to the frequency of thebroadcasting station selected. The push rod may then be releasedwhereupon the spring 28 will return said rod to its normal forwardmostposition.

After the first selector member IT has been thus adjusted to tune thecondenser to a given station, a second one of the selector members maybe adjusted in a similar manner for tuning the condenser to a secondstation. In like manner, the remaining selector members i! may beadjusted for tuning the condenser to a corresponding one of a group ofselected stations. After the selector members have all been properlyadjusted, it will be obvious that the receiving set may be quickly andeasily tuned to the frequency of any one of said group of selectedstations by merely pressing inwardly on the proper push bar 2 I.

To explain more explicitly, let it be assumed that the heads 35 and 38of the selector member I1 to be actuated are positioned as illustratedin Figure 2. It will be observed that as the push rod 2| is movedinwardly against the action of the spring 28, the head 38, beingnormally nearer to the tie-rod 50 than the head 35 to the tierod 5|,will engage the tie-rod 50 prior to the engagement of the head 35 withthe tie-rod 5|. In other words, the selector member |1 will be in theposition illustrated in Figure 3 when the head 38 contacts the tie-rod50. As the selector member is moved inwardly to a greater distance, thehead 38 will rock the levers 45 about the axes of the studs 46 inadirection to move the rear ends of said levers connected with the links43 downwardly and thereby produce a corresponding downward movement ofthe rock arms 4|.

This downward movement of the arms 4| will produce a correspondingdownward movement of the rear ends of the levers 44 due to theconnection of said levers with the arms 4| by links 43. This downwardrocking movement of the levers 44 will produce movement of the tie-rod5| connected therewith toward the front side of the frame I so that thehead 35 and tie-rod will be moved in directions toward each other untilthe head 35 engages the rod 5 I, at which period in the operation of theselector member the heads 35 and 38 and the linkage mechanism will be inthe position illustrated in Figure 4. This rocking movement of thelevers 44 and 45 will, of course, produce a corresponding rotation ofthe shaft I5 and the rotor plates R of the condenser C connected withsaid shaft. As the push bar 2| is released, the spring 28 connected withthe corresponding control member will return the push rod 2| associatedtherewith to its normal outermost or inoperative positions, while thecondenser will remain in the set position.

In order to tune the set to another selected station of the group, it isonly necessary to push inwardly on the corresponding control member I1to bring the heads 35 and 38 thereof into engagement with the tie-rods50 and 5|. When both of said heads engage said tie-rods, the condenserwill be properly adjusted to the frequency of the station selected. Itwill be understood that the push rods 2|, when in their outermostinoperative positions, will maintain the selector heads 35 and 38 out ofthe path of movement of tie-rods 5'0 and 5| so that said rods are freeto be actuated by the heads associated with any one of the selectormembers H for adjusting the condenser. Also the condenser may beadjusted by the conventionally constructed tuning control of thereceiving set when the selector heads are in their operative positionsat one side of the path of movement of the tie-rods 50 and 5|.

The modified structure shown in Figures 8 and 9 is very similar inconstruction and operation to that shown in Figures 1 to 7, inclusive.This structure is adapted to actuate a drive shaft, as l5, which ispositioned either above or below the supporting frame I0. The driveshaft I5, in this instance, is shown as being positioned above the frameIII while the levers, as 44 and 45 and the links 43 and arm 4|, are ofsuch a length and form as to permit them to readily rotate the shaft I5upon engagement of any one of the manually operated selector or controlmembers I1 with the tie-rods 50 and 5|. In the structure shown in thesefigures, there is provided a set of levers 44' and 45' at each end ofthe frame ID. The levers 45 of each pair are constructed substantiallyalike except that one is a right-hand lever and the other is a left-handlever. Likewise, the levers 44 of each pair are constructedsubstantially alike except that one is made a right-hand leverand theother a lefthand lever. The rock levers 44' and 45 are of substantiallygoose-neck construction, as illustrated in Figure 8, so as to providesufficient movement of the levers to produce a maximum rotation of theshaft I5 without their coming into contact with said shaft. In thisinstance, the drive shaft I5 is supported by any suitable meansexteriorly of the frame I0, such as indicated at 55, Figure 9, which maycomprise a portion of the housing or frame supporting the variablecondenser to which the shaft I5 is connected.

In Figures 10 and 11, the linkage mechanism connecting the tie-rods 50and 5| with the drive shaft I5 is adapted more particularly foroperating the shaft I5 when said shaft is positioned at one side of theframe I0, either above or below said frame, and in substantiallyparallel relation with the push rods 2| instead of transversely of saidpush rods as in the structures shown in Figures 1 and 8. In thestructure shown in Figures 10 and 11, the drive shaft I5 may besupported at one side of the frame In by any suitable means, as by thecondenser frame indicated at 55, secured to the chassis of the radioreceiving set. As shown more particularly in Figure 10, the rock levers5B and 51 connected with the tie-rods 50 and 5| positioned at one end ofthe frame I I] are substantially L-shaped members which are pivotallymounted upon the pivotal post or stud 41 carried by the frame I0. Theshorter legs, as 56' and 51 of the levers 56 and 51, extend in oppositedirections from the pivotal stud 41 and support adjacent ends of thetierods 50 and 5| respectively. The opposite ends of the tie-rods 50 and5| are similarly supported by a pair of rock levers 58 rotatably mountedupon a pivotal stud 41 positioned in the opposite end of the frame Infrom the levers 5B and 51. These levers 58 are relatively short memberswhich function to rotatably support the adjacent ends of the tie-rods 50and 5| only and are not connected, in this instance, directly with thedrive shaft I5. The tie-rods 50 and 5| are preferably fixedly connectedwith the levers 56, 51 and 58 to provide a relatively rigid operatingstructure, that is, one which will function without flexing, forproducing the required movement of shaft I5 irrespective of theparticular selector member I1 by which said operating structure isactuated.

The drive shaft I5, in this instance, is provided with a single rock arm4| constructed and secured to the shaft I5 in the manner described aboveand shown in Figures 1, 3, 4 and 5 of the drawings. The outer ends ofthe arm 4| are pivotally connected with links 43' which, in turn, arepivotally connected to rock levers 59 and 60, as shown in Figures 10 and11. These levers 59 and 60, as shown, are pivotally connectedintermediate their ends, as at 6|, to the supporting member 55 at oneside of the shaft I5 to rock about a common axis extending in spacedsubstantially parallel relation with shaft i5. The ends of the levers 59and 60, at the opposite side of the pivot -6l to that of the links 43,are operatively connected with the rock 1evers 56 and 51, respectively,by tie-rods 62 and 63.

It will now be observed that inasmuch as the rock levers 59 and 60rotate about an axis extending substantially parallel with the shaft l5and in substantially right angular relation with the axis of rotation ofthe levers 56 and 57, the shaft l5 will be rotated in one direction orthe other by the engagement of the heads 35 and 38 with the tie-rods 50and 5|, depending upon which of the heads is first to engage a tierod.

Furthermore, it will be noted that in each of the three differentstructures illustrated in the drawings, there is a double linkagemechanism connecting the actuating elements or tie-rods 5i! and 5| withthe adjacent portion of the drive I shaft l5, one of these linkagemechanisms being adapted when operated by its respective actuatingelement, to move the drive shaft I5 in one or a clockwise direction andthe other linkage mechanism being adapted, when operated by itsrespective actuating element, to move the drive shaft I5 in the oppositeor counterclockwise direction. This arrangement of the linkagemechanisms provides a structure which will accurately position the driveshaft I5 upon each inward movement of a selector member I! without thenecessity of constructing the linkage mechanism with a high degree ofprecision. Also, this structure will function efficaciously over anextended period of time, even though lost motion is introduced thereinas a result of wear taking place at the joints or pivotal connectionsbetween the levers and links;

While I have shown and particularly described the preferred embodimentsof my invention, I do not wish to be limited to the exact constructionshown as various changes, both in the form and the relation of partsthereof, may readily be made without departing from the spirit of theinvention as set forth in the appended claims.

I claim:

1. A tuning unit for a radio receiver comprising a drive shaft adaptedto be operatively connected to the shaft of a variable condenser, areciprocating selector rod mounted for movement at one side of the driveshaft, means for actuating said shaft including a linkage mechanismconnected therewith and having a pair of operating members arranged atopposite sides of the selector rod, spaced actuating elements mounted onsaid selector rod movable into and out of operative engagement with saidoperating members during the reciprocation of said rod, and manuallyoperated means for actuating the selector rod.

2; A tuning unit as in claim 1 wherein the actuating elements areadjustably connected with the selector rod for movement with respect toeach other whereby the degree of movement of the linkage mechanismproduced by the engagement of said elements with the operating membersmay be varied.

3. A tuning unit as in claim 1 having spring means connected with theselector rod for yieldingly maintaining the actuating elements out ofengagement with said operating members.

4. A mechanical tuning unit for a radio receiver comprising a pluralityof manually operated selector members, a drive member mounted in spacedrelation to said selector members, an

actuating mechanism connected to the drive member, said mechanism havinga pair of operating members therefor common to all of said selectormembers and arranged at opposite sides of said selector members, each ofsaid selector members having spaced actuating elements movable into andout of operative engagement with said operating members during theoperation of said selector members, and means for adjusting theactuating elements toward and from each other to cause a variation inthe degree of movement of the operating members and therefore of thedrive member produced thereby.

5. A tuning unit for a radio receiver comprising a frame, a plurality ofselector rods connected with said frame for reciprocating movement Withrespect to each other, a drive shaft adapted to be connected with theshaft of a variable condenser rotatably connected with said frame at oneside of said selector rods, actuating means for operatively connectingthe selector rods with said drive shaft including a pair of linkagemechanisms rotatably connected to the frame to rock about a fixed axisand connected to said drive shaft, a pair of tie-rods connecting saidlinkage mechanisms arranged at opposite sides of said axis of rotationof the linkage mechanisms, a pair of actuating elements on each of saidselector rods movable into and out of engagement with a respective oneof said tie-rods during the reciprocating movement thereof for actuatingthe linkage mechanisms, and manually operated means for actuating saidselector rods.

6. A tuning unit as in claim 5 wherein the selector rods are rotatablymounted and have right and left screw-threaded engagement with saidactuating elements whereby rotation of each selector rod will producerelative movement of the actuating elements connected therewith towardor from each other for varying the degree of movement of the tie-rodsproduced thereby during. the reciprocation of said selector rod.

7. A tuning unit as in claim 5 wherein the selector rods are rotatablymounted and have right and left screw-threaded engagement with saidactuating elements whereby rotation of each selector rod will producerelative movement of said actuating elements connected therewith towardor from each other for varying the degree of movement of the tie-rodsproduced thereby during the reciprocation of said selector rod, andspring means interposed between the selector rods and said frame foryieldingly urging the rods in one direction to maintain the actuatingelements out of engagement with the tie-rods.

8. A tuning unit for a radio receiver comprising a frame, a plurality ofreciprocative selector members mounted in said frame in spacedsubstantially parallel relation to each other, a drive shaft adapted tobe operatively connected with the shaft of a variable condenserrotatably mounted in said frame at one side of and extendingtransversely to said selector members, a plurality of pairs of actuatingelements, one pair for each selector member, the elements of each pairbeing arranged in spaced relation to each other, rock members pivotallyconnected with said frame to swing about an axis extending substantiallynormal to the axes of reciprocation of the selector members, a, pair ofoperating members connected with said rock members at opposite sides ofthe axis of rotation thereof and arranged in the path of movement ofeach pan of actuating elements to be alternately engaged thereby so thatthe rock members will be rocked in one direction or the other dependingupon which of the operating members is first engaged by an actuatingelement, and means operatively connecting the rock members to said driveshaft,

9. In a tuning unit for a radio receiving apparatus, in combination, aframe, a selector rod supported by said frame to extend forwardlytherefrom and for both longitudinal and rotary movements with respectthereto, a condenser drive shaft rotatably supported by the frame, apair of selector elements slidably supported by the frame and havingscrew-threaded connection with the selector rod to be reciprocated bythe rod in unison therewith during said longitudinal movement of saidrod and to be moved relative to the rod toward or from each other duringsaid rotary movement of said rod, a pair of operating elements arrangedat one and the same side of the selector elements in the path ofmovement thereof, means pivotally connecting the operating elements tothe frame So that said operating elements may swing about a fixed axisextending substantially midway between said operating elements andtransversely to the axis of movement of the selector rod, meansassociated with said pivotal means for operatively connecting theoperating elements to the drive shaft, said selector rod having afingerpiece connected with the forward end thereof by which said rod maybe both moved longitudinally to bring the selector elements intoengagement with the operating elements and rotated during saidengagement of said elements with each other to alter the relativeposition of the selector elements and of the position of the operatingelements produced thereby.

10. In a tuning unit for a radio receiving apparatus, in combination, aframe, a selector rod supported by said frame to extend forwardlytherefrom and for both longitudinal and rotary movements with respectthereto, a drive shaft rotatably supported by the frame adapted to beconnected with a variable condenser, means perably connecting theselector rod with the shaft comprising a pair of selector elementsslidably supported by the frame and having screwthreaded engagement withsaid selector rod to be reciprocated by said rod in unison therewithduring said-longitudinal movement of the rod and to be moved relative tothe rod toward or from each other during said rotary movement of saidrod, an operating mechanism connected to the shaft and including a pairof operating elements, each of said operating elements being arranged atthe rear side of a corresponding one of the selector elements in thepath of movement thereof, and means including a pivotal member arrangedintermediate the operating elements for rotatably connecting saidoperating elements to the frame, the forward end of said selector rodbeing provided with a tool engaging means by which said rod may be bothmoved rearwardly to bring the selector elements into engagement with theoperating elements and rotated during said engagement of said elementswith each other to alter the position of the selector elements and ofthe position of the operating elements produced thereby.

11. A mechanical tuning unit for a radio re ceiver comprising a frame, amanually operated selector rod supported by said frame for longitudinalreciprocative movement with respect to said frame, a rotatable driveshaft adapted to be connected to the shaft of a variable condenser, saidshaft being mounted at one side of the frame in spaced relation thereto,means operably connecting the selector rod to the drive shaft wherebyreciprocative movement of said rod will produce rotary movement of saidshaft including a pair of operating elements mounted at opposite sidesof the selector rod to swing about a common axis, means actuated by theselector rod for swinging the operating'elements to predeterminedpositions in their path of movement, and a linkage mechanism operativelyconnecting the operating elements with said shaft.

' 12. A tuning unit as in claim 11 wherein the drive shaft is arrangedto extend in substantially parallel relation with the selector rod, andthe linkage mechanism includes a rock lever having anfaxis of swingingmovement extending substantially parallel with the axis of rotation ofthe drive shaft in fixed relation therewith.

13. In a tuning unit for radio receiving apparatus, in combination, aframe, a selector rod supported by said frame for longitudinal movementwith respect thereto, a drive shaft supported by the frame in spacedrelation to said selector rod and drive members, actuating means foroperatively connecting the selector rod with said drive shaft includinga pair of drive members connected with said selector rod to movetherewith and spaced from each other longitudinally of said rod, a pairof driven elements one for each drive member, said driven elements beingpivotally connected to the frame to rock about a common axis, and a pairof linkage mechanisms connecting the drive shaft with the drivenelements respectively, one of said driven elements and the linkagemechanism therefor being arranged to rotate the drive shaft in onedirection and the other driven elements and the linkage mechanismassociated therewith being adapted to rotate the drive shaft in theopposite direction when said driven elements are operated by theirrespective drive members.

14. In anautomatic tuning device, a member movable on an axis for tuningpurposes and means to move said member to a predetermined position, saidlast mentioned means comprising a manually translatable element and apair of positioning means on said element for moving said firstmentioned means and for fixing it in position by contacting it on eachside of its axis, said manually translatable element bearing means forchanging the position of said positioning means and accessible at an endof said manually translatable element.

15. In a device of the character described, means pivoted on its axis, aplunger longitudinally movable in a direction transverse to and throughsaid axis, longitudinally movable means on said plunger for contactingsaid pivoted member respectively on each side of its said axis, andmeans on said plunger for moving said longitudinally movable meanssubstantially equally and in opposite directions.

16. In a device of the character described, means pivoted on its axis, aplunger longitudinally movable in a direction transverse to and throughsaid axis, longitudinally movable means on said plunger for contactingsaid pivoted member respectively on eachside of its said axis, and meanson said plunger for moving said longitudinallymovable meanssubstantially equally and in oppositedirections, said last mentionedlongitudinally movable means comprising a shaft having threadedengagement with said longitudinally movable means.

17; In a device of the character described, means pivoted on its axis, aplunger longitudinally movable in a direction transverse to and throughsaid axis, longitudinally movable means on said plunger for contactingsaid pivoted member respectively on each side of its said axis, andmeans on said plunger for moving said means substantially equally and inopposite directions, said last mentioned means comprising a shaft havingthreaded engagement with said longitudinally movable means, an end ofsaid shaft constituting a means whereby said plunger may be moved.

18. In a device of the character described, means pivoted on an axis andmeans for moving said pivoted means, said last mentioned meanscomprising a plunger, adjustable positioning means on said plunger fortwo-way location of said pivoted means and comprising a pair ofabutments each adapted to act upon said pivoted means on a differentside of its axis, and a common means for moving said plunger and forvarying the position of said adjustable positioning means.

ARTHUR B. WINCHELL.

